“This software product already does 90% of what we need.” If only I got a cent every time I have heard this. It is the most ridiculous argument there is for standard software versus custom built software.

When companies or teams select software, it is a common mistake to look at the percentage of functionality covered. Doesn’t a 90% coverage mean it’s just a small step to get exactly what you want!?

Adding a floor

Consider a high rise. 50 floors of exquisite architecture, exactly in the right location. And it’s super affordable. If only it had 2 extra floors…

The solution might be simple. If you need 2 floors added on top, that might be a viable option. Perhaps the elevator won’t reach them, but it wouldn’t be extremely expensive to do.

It’s a slightly different story when you need a double basement underneath the building. It’s still possible, but far more expensive.

The ultimate case however, is if you absolutely need to add two floors at the bottom or in the middle of the building. I am sure it can be done somehow, but I bet it’s cheaper to build a new building.

Adding a software floor

All three cases with the building add 10%, but it seems obvious that they are not equal. In software however, we somehow assume they are equal.

So whenever you consider ‘adding a floor’ to standard software, make sure you fully understand exactly what the impact is. No matter how configurable the software is, how many happy customers there are that ‘do things in the same way for 90%’ – if you try to add the wrong floor, it’s going to cost you.